Passenger vehicles may include fuel cell (“FC”) systems to power certain features of a vehicle's electrical and drivetrain systems. For example, a FC system may be utilized in a vehicle to power electric drivetrain components of the vehicle directly (e.g., using electric drive motors and the like) and/or via an intermediate battery system. Hydrogen is one possible fuel that may be used in a FC system. Hydrogen is a clean fuel that can be used to efficiently produce electricity in a FC. A hydrogen FC system is an electrochemical device that may include an electrolyte between an anode and a cathode. The anode receives hydrogen gas and the cathode receives oxygen or air. The hydrogen gas is dissociated in the anode to generate free hydrogen protons and electrons. The hydrogen protons may be selectively conducted across the electrolyte. The electrons from the anode cannot pass through the electrolyte, and thus are directed through a load to perform work before being sent to the cathode. The hydrogen protons react with the oxygen and the electrons in the cathode to generate water.
Proton exchange membrane fuel cells (“PEMFC”) may be used in FC-powered vehicles. A PEMFC generally includes a solid polymer electrolyte proton conducting membrane, such as a perfluorosulfonic acid membrane. An anode and cathode included in a PEMFC may include finely divided catalytic particles (e.g., platinum particles) supported on carbon particles and mixed with an ionomer. A catalytic mixture may be deposited on opposing sides of the membrane.
The ability to remove anion contaminant from the cathode is a consideration in achieving continued PEMFC system performance over time. To improve conditions for cathode anion contaminant removal, conventional PEMFC systems may include low cathode stoichiometry, thereby forcing the voltage of the PEMFC system lower under moderate load. Such methods, however, may result in lower stability and poorer current distribution across active catalyst areas in the PEMFC system.